tusntuk2
Active Member
Holiday Greetings, AK'ers!
My beloved Pioneer SX-727 blew an internal .5 fuse, so I checked it out. AK threads suggested the power supply or the protection circuit were common culprits. You might remember that the Protection Boards in the SX-727, and several other SX and SA series amps, are a bit frustrating because of multiple variations. Pioneer did not publish all the schematics and pcb diagrams, either. So I was delighted to find the correct PCB picture in Biro's HFE "Diagrams" for the SA-8100, labeled simply "AWM-027". I compared it part by part to my board to confirm every component, visibly, with color codes, and finally with a DVM when necessary. I feel confident it is the D variation in the PCB foil side diagram.
Years ago someone had redrawn or found a working schematic for the AWM-027. I tried to draw in the changes for the D variation, as shown here. Would you like to take a look and see if it is functional? Is it correct? I am not an EE, I'm a hands on mechanic. I have succeeded with recapping projects by being slow, singular and careful, but when it comes to understanding exactly how this transistor circuit works, I fall short! Maybe you can help?
After that, I'll be trying to fix the problem, in another thread.
View media item 29262
Thanks for checking it out! Thought I'd share - maybe it will help.
Jingle, jingle!
Jim
My beloved Pioneer SX-727 blew an internal .5 fuse, so I checked it out. AK threads suggested the power supply or the protection circuit were common culprits. You might remember that the Protection Boards in the SX-727, and several other SX and SA series amps, are a bit frustrating because of multiple variations. Pioneer did not publish all the schematics and pcb diagrams, either. So I was delighted to find the correct PCB picture in Biro's HFE "Diagrams" for the SA-8100, labeled simply "AWM-027". I compared it part by part to my board to confirm every component, visibly, with color codes, and finally with a DVM when necessary. I feel confident it is the D variation in the PCB foil side diagram.
Years ago someone had redrawn or found a working schematic for the AWM-027. I tried to draw in the changes for the D variation, as shown here. Would you like to take a look and see if it is functional? Is it correct? I am not an EE, I'm a hands on mechanic. I have succeeded with recapping projects by being slow, singular and careful, but when it comes to understanding exactly how this transistor circuit works, I fall short! Maybe you can help?
After that, I'll be trying to fix the problem, in another thread.
View media item 29262
Thanks for checking it out! Thought I'd share - maybe it will help.
Jingle, jingle!
Jim